The invention relates to a cylinder head casting for a multicylinder combustion engine with a plurality of cylinder portions. Each cylinder portion includes gas changing channels, valve guides and bolt holes for one cylinder. The cylinder head is provided with a deck face designed to rest on a cylinder block. A valve drive pan is positioned opposite the deck face. The cylinder head has two longitudinally extending side faces and two end faces. The cylinder head has a cast longitudinal cooling water channel which extends along the plurality of cylinder portions. The longitudinal cooling water channel includes cooling water entry apertures and cooling water exit apertures designed to be connected to cooling water channels in the cylinder block. Furthermore, the invention relates to a method of casting such a cylinder head casting and to a casting core suitable for carrying out the casting method.
In the case of engines subject to high loads due to increasing performance density, the formation of vapor bubbles constitutes a greater and greater problem in the cooling water system. The vapor bubbles must be avoided because of the deterioration in heat transfer and the resulting impermissible thermal stresses. In modern two valve, three valve, four valve or five valve engines, with 2, 3, 4 or 5 valves per cylinder, the problem is intensified as the longitudinal cooling water channel has more and more branches and clefts. Thus, portions are formed with a reduced cooling water flow speed, which encourage the formation of vapor bubbles.
A cylinder head casting is known from DE 28 39 199 C2. A longitudinal cooling water channel extends in the vicinity of a side face on the inlet gas channel side. Transverse cooling water channels are provided as bores. The bores are connected to niche-like water chambers which can be deformed from their cores after casting towards the separating plane between the cylinder head and cylinder block. The bores serve to ensure a defined flow of cooling water.